Now you could drag and drop attachments from your local computer to Gmail without ever hitting the attach button and then browsing for your file. This feature is also available on the Mail application on a Mac. Just open the folder which contains your file and drag the file to the compose mail box. Gmail would recognize your attachment and would come up with a message advising you to drop your file in the box. Just drop it and the file would be attached.
The Gmail Team plans to enable this feature on other browsers too, but currently it is only active on Google Chrome and Mozilla Firefox.